Siltation also clogs the gills of fish and the breathing apparatuses of 

 invertebrate organisms, which serve as food for fish and birds. Eroded soil 

 that has settled on the bottom of an aquatic system can smother food items of 

 bottom- feeding fish and may render the bottom unsuitable for certain bottom- 

 spawning fish. 



Instream and nearstream construction activities may have substantial impacts 

 on riverine systems. Instream construction may involve the placement of dikes 

 of rock, timber, or other material within a stream with the objective of 

 modifying streamflow. Or it may involve construction of shoreline or 

 midstream structures, such as boat launching ramps, piers, or bridge 

 abuttments , which modify the stream environment. Nearstream construction 

 refers to any construction activity (e.g., home-building and road 

 construction) that occurs near enough to a stream to have discernable effects 

 on it. 



Instream construction almost inevitably results in disturbance of stream 

 sediments. Most types of near stream construction involve earth-moving and/or 

 vegetation removal, which increases the soil's susceptibility to erosion. 

 Frequently, much of the eroded material from construction sites on or near 

 streambanks is washed into the stream. The increased movement of stream silt 

 or eroded soil particles increases the turbidity (cloudiness) of the stream 

 water. Frequently, plant nutrients, especially phosphorus, that are bound to 

 soil particles are released when the particles are eroded and carried into the 

 stream. This may result in eutrophication of the stream (see "Domestic 

 Sewage" above). Heavy metals, such as chromium (from tanneries) and mercury 

 (transported by air currents), may be found in some Maine soils and sediments, 

 as may certain pesticides and other toxic materials. These potentially 

 harmful materials may be released when soils and stream sediments are 

 disturbed. 



In addition to sediment disturbance, instream construction may have direct 

 effects on the stream environment through the structures placed in the stream. 

 These structures frequently deepen channels by obstructing stream flow along 

 the streambanks (Yorke 1978). This may cause localized flooding, as high 

 flows that would otherwise be carried by the channel with no difficulty are 

 held up and spill over onto the floodplain. The placement of structures 

 within a stream often increases the diversity of stream habitats available, 

 thus having a potentially beneficial effect on the number and diversity of 

 stream organisms inhabiting the site. However, if siltation occurs in the low 

 water velocity pockets downstream of the emplaced structures, habitat 

 diversity in these areas will be reduced. Construction activities that remove 

 streambank vegetation alter the light penetration and temperature regimes of 

 the stream. This in turn affects the composition of stream biological 

 communities . 



REGULATIONS GOVERNING HUMAN ACTIVITIES IN THE BIOLOGICAL SYSTEMS OF COASTAL 

 MAINE 



The regulations governing freshwater, (palustrine, lacustrine, and riverine 

 systems), tidal (marine, estuarine, and riverine systems) and terrestrial 

 habitats are summarized below. 



3-49 



10-80 



